A dialog system has a text or audio interface, allowing a human to interact with the system.
Particularly advantageous are ‘natural language’ dialog systems that interact using a language syntax that is ‘natural’ to a human. A dialog system is a computer or an Interactive Voice Response (IVR) system that operates under the control of a dialog application that defines the language syntax, and in particular the prompts and grammars of the syntax. For example, IVRs such as Nortel's Periphonics™ IVR are used in communications networks to receive voice calls from parties. An IVR is able to generate and send voice prompts to a party and receive and interpret the party's voice responses made in reply. However, the development of a dialog system is cumbersome and typically requires expertise in both programming and the development of grammars that provide language models. Consequently, the development process is often slower than desired.
A particular difficulty encountered when developing a dialog system is the inability to predict (i) the effort required to develop the system, and (ii) the speech recognition accuracy when the dialog system uses speech recognition. These are important issues for developers of dialog systems, because a decision to develop a dialog system based on an underestimate of the effort required, and/or an overestimate of the recognition accuracy that will be achieved, can result in an expensive investment that does not deliver the required results. State of the art speech recognition systems use language models, typically in the form of probabilistic, context-free attribute grammars, to improve performance. If the grammar coverage is too small, a large proportion of utterances received by the system will not be correctly recognised because they are not included in the allowed set of responses. On the other hand, this will also occur if the grammar coverage is too large, because the speech recognition task becomes too difficult.
It is desired to provide a system and process for use in developing a dialog system that alleviate one or more of the above difficulties, or at least provide a useful alternative to existing development systems and processes.